Yes, they are exist. I know two: Ubuntu Studio and 64 Studio. They are free to download and use (GPL, Open Source)
Both OS are based on Linux (for me it's a big plus) and have a lot of useful programs already on board. One of those programs is Ardour - on both systems. It's a digital audio workstation. I wrote about it in post: ”10 great, free software programs for musicians and sound engineers”. It's something very useful for home and pro recording studios.
Ubuntu Studio an 64 Studio have also many other software, not only for audio. They are made for people connected with media production (also graphic designers and video editors). When you will install one of them, you will get all basic software needed to start some home recording studio.
Personally, I was using Ubuntu Studio with very good results. Now I'm using Ubuntu also, but it's a standard (not Studio) version, which I customized a little for my own purposes. I didn't work a lot with 64 Studio, but it seems to be well made. Both OS have many pro users (professional audio, graphic studios etc.), so they just can't be bad.
They have also typical office software, so don't think that you need two systems – one for audio work, one for office work. They have OpenOffice, e-mail clients, web browsers (Firefox) etc.
I am writing this text mostly for those of you, who are stuck on Windows and don't see, that there are many, very good alternatives on the market - especially for audio.
As you can see, it's more a presentation than a review, so if you are interesting in one of these operating system, here are links:
